Why is the Hup Battery in a steel case?

Each 2 volt cell of the battery is built into a rugged plastic jar. The jar is very good at containing the acid, but is not suitable for supporting the heavy lead plates. The steel case does two things. It protects the battery while in shipment and also supports the side walls of the cells preventing slumping of the jar. Never leave the cells out of the case for more than a few hours.